The invention relates to a cylinder for guiding endless webs of paper or board, especially for coating equipment or slitter/winders.
It is already known from U.S. Pat. No. 3,091,563, on suction breast rolls exhibiting a shell provided with perforations in order to carry away the water pressed into the interior of the roll, to provide an internal body which is arranged eccentrically to the hollow roll, in order to intensify removal of the pressed-out water by the generation of a vacuum in the resulting space of a sickle-shaped cross-section and in particular to prevent a rewetting. For this purpose a complete hollow cylinder was used.
In paper mills there is often a problem to conduct a web of material, in particular of paper or board, over a cylinder without losing the adherence of the web of material even at very high speeds of more than 800 m/s. When air is drawn into the up-running area of the web of material on the cylinder, a thick boundary layer is formed on the cylinder surface, which renders a firm contact of the web of material on the cylinder impossible.